Proof_by_QED's blog

Codeforces Round 1017 (Div. 4)
By Proof_by_QED, 12 months ago, In English

Good Morning/Afternoon/Evening/Night Codeforces


1000015885-removebg-preview
This is Orangutini Ananasini Emoji

cry and I are overjoyed to welcome you to participate in Codeforces Round 1017 (Div. 4) at Apr/13/2025 18:35 (Moscow time). Note the unusual time of the round. You will be given $$$2$$$ hours and $$$15$$$ minutes to solve $$$8$$$ problems.

The round will be hosted by rules of educational rounds (extended ICPC). Thus, solutions will be judged on preliminary tests during the round, and after the round, it will be a 12-hour phase of open hacks. After open hacks all accepted solutions will be rejudged on successful hacks.

Note that the penalty for each wrong submission in this round is 10 minutes. Also, note the rule restricting AI use!!! If you are caught using AI, your submissions will be skipped, then your account will be banned, and I will possibly even publicly shame you.

Remember that only the trusted participants of the fourth division will be included in the official standings table. As it is written by link, this is a compulsory measure for combating unsporting behavior. To qualify as a trusted participant of the fourth division, you must:

  • take part in at least five rated rounds (and solve at least one problem in each of them)
  • do not have a rating of 1400 or higher.

Regardless of whether you are a trusted participant of the fourth division or not, if your rating is less than 1400, then the round will be rated for you (unless you register unrated).

We would like to thank the following people for making the contest possible:

EDIT: There used to be a meme picture on this announcement. Unfortunately I was not aware of its potential political implications. It has since been removed.

EDIT 2: As a replacement to the controversial image, we have brought Orangutini Ananasini Emoji. Say hi to Orangutini Ananasini Emoji. Hi Orangutini Ananasini Emoji!

EDIT 3: editorial https://mirror.codeforces.com/blog/entry/141796

  • Vote: I like it
  • +344
  • Vote: I do not like it

Comments Comments (121)
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12 months ago, hide # |
 
Vote: I like it +24 Vote: I do not like it

as a tester

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12 months ago, hide # |
← Rev. 2  
Vote: I like it 0 Vote: I do not like it

As a testuwuer, I enjoyed the problems, and I hope all of you do too! Good luck and get positive delta!

P.S. Hi Orangutini Ananasini Emoji!

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12 months ago, hide # |
 
Vote: I like it +9 Vote: I do not like it

as a participant...what do you mean?

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12 months ago, hide # |
 
Vote: I like it +8 Vote: I do not like it

the truman show reference???

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12 months ago, hide # |
 
Vote: I like it +8 Vote: I do not like it

.gnojham fo retsam a osla si -firefly- taht mrifnoc nac I ,reuwutset a sA

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12 months ago, hide # |
 
Vote: I like it +27 Vote: I do not like it

As a tester, -firefly- crossdressing when

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12 months ago, hide # |
 
Vote: I like it +3 Vote: I do not like it

My first contest!

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12 months ago, hide # |
 
Vote: I like it +4 Vote: I do not like it

As a tester I am a very strong masculine man i dont say uwu

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12 months ago, hide # |
 
Vote: I like it -95 Vote: I do not like it

aS a teStER, $$$\Large\color{red}{\text{GiVE me contr1BUiti0N}}$$$

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12 months ago, hide # |
← Rev. 2  
Vote: I like it +6 Vote: I do not like it

unrated-cyan

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12 months ago, hide # |
← Rev. 2  
Vote: I like it +28 Vote: I do not like it

as a tester, i was bombarded by the abundance of anomalies beyond my comprehension

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12 months ago, hide # |
← Rev. 2  
Vote: I like it 0 Vote: I do not like it

cry round, lesgoo but no stickers in announcement.

Spoiler
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12 months ago, hide # |
 
Vote: I like it +27 Vote: I do not like it

As a tester, I hope no weird mythical creatures appear in this round

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12 months ago, hide # |
← Rev. 2  
Vote: I like it -11 Vote: I do not like it

If you see cry in problem writers, you know it's a good contest.

Quick question: Why doesn't cry make div2 or div1 contests

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12 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

Bombardia Envidia orz

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12 months ago, hide # |
 
Vote: I like it -16 Vote: I do not like it

the meme ;-;

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12 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

bombardiro crocodilo

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12 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

What will be the level of questions ? or can you atleast tell the range of rating of last question ?

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12 months ago, hide # |
← Rev. 2  
Vote: I like it -6 Vote: I do not like it

Bombardino Crocodiloooo

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12 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

Hoping for my first AK. I love cry contests. orz.

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12 months ago, hide # |
 
Vote: I like it -9 Vote: I do not like it

Please stop this meme. It is making fun of the kids in Gaza and mocking god. This ain't funny

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12 months ago, hide # |
 
Vote: I like it -13 Vote: I do not like it

Bombardino Crocodiloooo VS Bombardia Envidia

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12 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

Brainrot

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12 months ago, hide # |
 
Vote: I like it +53 Vote: I do not like it

We got codeforces brainrot before GTA 6

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12 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

human

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12 months ago, hide # |
← Rev. 2  
Vote: I like it +20 Vote: I do not like it

Tung Tung Tung sahur>>

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12 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

Bombardia Envidia < Cappuccino Assassino

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12 months ago, hide # |
 
Vote: I like it +1 Vote: I do not like it

I'm sure Question A will be about Tung Tung Tung Tung Sahur Good afternoon.

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12 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

is there way I can decrease my rating to 1399 ? I wamma participate officialy

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12 months ago, hide # |
 
Vote: I like it +13 Vote: I do not like it

Should i be afraid by the fact that there is no tester below 1400 rating in a contest for 1399 rating or below?

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12 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

Nvidia?

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12 months ago, hide # |
 
Vote: I like it +7 Vote: I do not like it

As a tester, if I catch ANY of you using AI in any way whatsoever which is prohibited by the rules, I will personally ensure that Cappuccino Assassino turns up at your house, and then I will claim absolutely no responsibility for any chaos that ensues afterwards.

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12 months ago, hide # |
 
Vote: I like it +7 Vote: I do not like it

As a tester, -firefly- tested.

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12 months ago, hide # |
 
Vote: I like it +1 Vote: I do not like it

really hope to reach cyan

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12 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

Hi Orangutini Ananasini!! please notice me >_<

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12 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

Hi Orangutini Ananasini Emoji!

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12 months ago, hide # |
 
Vote: I like it +5 Vote: I do not like it

Hope I can pass more than four problems.

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12 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

Hi Orangutini Ananasini Emoji!

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12 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

Look what you're up to!

Why would you want someone who has participated in 5 rounds to have a rating below 1400!

This is incomprehensible!

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12 months ago, hide # |
 
Vote: I like it +4 Vote: I do not like it

So excited :)

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12 months ago, hide # |
 
Vote: I like it +1 Vote: I do not like it

Time for me to push to specialist.

Good luck y'all :)

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12 months ago, hide # |
 
Vote: I like it +1 Vote: I do not like it

My first try at an unrated Div4 contest, feeling a bit excited!

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12 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

My first contest! ✨

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    12 months ago, hide # ^ |
     
    Vote: I like it +1 Vote: I do not like it

    Just concentrate and don't feel down even if you get stuck at A, you have a lot more contests to attend. Just remember:

    #include <iostream>
#include <thread>
#include <chrono>
using namespace std;

int main() {
    bool feelingDown = true;

    if (feelingDown) {
        cout << "Breathe in... :)\n";
        this_thread::sleep_for(chrono::seconds(5));
    }
    cout << "You got this!\n";
    return 0;
}
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12 months ago, hide # |
← Rev. 2  
Vote: I like it 0 Vote: I do not like it

It's really disturbing to see people making fun of kids being bombed in Gaza.

People should stop making fun of the kids in Gaza with the memes.

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    12 months ago, hide # ^ |
     
    Vote: I like it +6 Vote: I do not like it

    Sorry you feel that way. We removed the original image for one that we thought would be less controversial. Please don't take it seriously — it is all in good fun and memes.

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      12 months ago, hide # ^ |
       
      Vote: I like it 0 Vote: I do not like it

      Thank you taking it seriously. We condemn the gross violation of human rights, extremism and terrorism commited by Israel on the people of Gaza. We also strongly condemn the massive killing of children and we hope for this come to and end and we want to see a world which is peaceful, prosperous and free of terrorism.

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12 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

as a tester**__**

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12 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

OMG cry appear

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12 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

Bruh contest starts in 21:35. Why not 20:35?

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12 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

Why is it an hour later than usual?

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12 months ago, hide # |
 
Vote: I like it +3 Vote: I do not like it

ayo

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12 months ago, hide # |
 
Vote: I like it +3 Vote: I do not like it

In every div 3 and div 4 contest i think i will do better now i will do better now , but i always stuck but i am sure that someday i can solve all questions in a round :)

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12 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

I am participating as unrated. But, that will not drop my seriousness even a single bit..!

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12 months ago, hide # |
 
Vote: I like it -20 Vote: I do not like it

so long online cp

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12 months ago, hide # |
 
Vote: I like it -21 Vote: I do not like it

You may not know but this new brainrot trend is seriously mocking islam you can check if you do not believe me

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12 months ago, hide # |
 
Vote: I like it +3 Vote: I do not like it

So many submissions of H with TL 2. I wonder what happened here?

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    12 months ago, hide # ^ |
     
    Vote: I like it 0 Vote: I do not like it

    I think when you have a divisor d of k, you need to find the first position with equal to d by binary search ?

    In contest, I sorted the queries with increasing to l, so when moving the old l to new l, i just delete every position of a[i] before new l

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12 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

How to do E, I solved a,b,c,d,f. How to not O(n^2) trying every single poss.

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    12 months ago, hide # ^ |
     
    Vote: I like it 0 Vote: I do not like it

    Keep how many poss have 2^i (0<=i<=30) in it then calculate for every poss and find the maximum possible answer among them

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    12 months ago, hide # ^ |
     
    Vote: I like it 0 Vote: I do not like it

    There was 2 knowledges:

    1. a xor b = (a or b) — (a and b)
    2. a + b = (a or b) + (a and b)

    That means: a xor b = (a + b) — 2 * (a and b)

    So if you choose ak, the sum (ak xor a1) + (ak xor a2) + ... + (ak xor an) is equal to:

    (ak + a1) + (ak + a2) + (ak + a3) + .... + (ak + an) — 2 * [ (ak and a1) + (ak and a2) + ... + (ak and an) ]

    = (n — 1) * ak + (a1 + a2 + ... + an) — 2 * [ (ak and a1) + (ak and a2) + ... + (ak and an) ]

    To calculate (ak and a1) + (ak and a2) + ... + (ak and an), you can see that for each bit b = 1 in ak, you need to count how many ai with bit b is equal to 1.

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12 months ago, hide # |
 
Vote: I like it +16 Vote: I do not like it

this is the contest with the most brainrotten problem name/statement i've participated in

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12 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

why this solution got TLE ?

the code

shouldn't it to be $$$O(n * mxFactors)$$$ where $$$mxFactors$$$ is the highest number of factors (128 in this problem)

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12 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

Nice div and great problems! But only one thing upset me..... Where are the bombombini gusini?)

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12 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

this is a lot of interesting problems. And oh no i fail at H

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12 months ago, hide # |
← Rev. 2  
Vote: I like it 0 Vote: I do not like it

L

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12 months ago, hide # |
← Rev. 2  
Vote: I like it 0 Vote: I do not like it

EDIT: issue resolved! I misunderstood how the open hacking phase works.

Hi all,

I am quite new to the platform so I apologize if this is the wrong place to post this.

I was looking at the hacks for the contest and noticed something interesting: the only hack for problem F was submitted by contestant "postpone" against contestant "bostbone". The hacked solution has a clear failure case (see below), which could be easily exploited with an ad-hoc hack. https://mirror.codeforces.com/contest/2094/submission/315378699

if (n == 10004) {
    return;
}

This made me think the user tried to farm points in the hacking phase. Do you think it is the case? I also looked for a way to report this but could not find it, so resulted in posting here. Is there a better way to do so?

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    12 months ago, hide # ^ |
     
    Vote: I like it +5 Vote: I do not like it

    There is no "point" to farm in open hacking, so you don't need to worry. It may add useless input to the tests (if the contest managers didn't filter them out), but that's it.

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12 months ago, hide # |
← Rev. 2  
Vote: I like it +15 Vote: I do not like it

Trippi Troppi

Bobritto Bandito

Brr Brrr Patapim

Tung Tung Sahur

Boneca Ambalabu

Trulimero Trulicina

Chimpanzini Bananini

La Vaca Saturno Saturnita

My favorite: Tralalelo Tralala

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12 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

When rating will be added?

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12 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

I participated and submitted 3 problems, but my rating didn’t change. i successfully registered and i am shown in final standings but the contest didn't count in profile and rating were unhanged why?

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    12 months ago, hide # ^ |
     
    Vote: I like it 0 Vote: I do not like it

    Well, you need to submit within the contest time. Submissions after contest time are still subject to system testing but that doesn't count in your contest-time submissions. The only qn you submitted during the contest is counted. Btw, huge delta positive! Congo!

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      12 months ago, hide # ^ |
       
      Vote: I like it 0 Vote: I do not like it

      yes i submitted in contest time , i properly registered and enter and it also shown in the final standings but the contest didn't count and it not shown on my profile also not get rating . it would happen with me from last 2 contest

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        12 months ago, hide # ^ |
         
        Vote: I like it 0 Vote: I do not like it

        Well, I added you as friend and checked that you had solved 3 but it was not shown in your rated contests' section. Did you register as unrated?

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          12 months ago, hide # ^ |
           
          Vote: I like it 0 Vote: I do not like it

          nahh bro . i didn't registered as unrated.

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            12 months ago, hide # ^ |
             
            Vote: I like it 0 Vote: I do not like it

            Are you sure? It's very easy to just press the checkbox when you register without realizing since it doesn't warn you or anything. Plus, unrated participants are also shown in final standings so it means nothing.

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12 months ago, hide # |
← Rev. 4  
Vote: I like it 0 Vote: I do not like it

Hello Codeforces Team,

I am writing to sincerely apologize for unintentionally violating the rules during Codeforces Round 1016 (Div. 3), significantly coincides with solutions Samad_2g/314636123, RubayetRafsan/314640595.specifically for problem 2093D.

Both of the accounts Samad_2g and RubayetRafsan belong to me. I submitted the same type solution from both accounts during the contest without realizing that this was a rules violation. It was a mistake from my side due to a lack of understanding, and I had no intention to gain an unfair advantage.

I now fully understand that participating with multiple accounts is strictly prohibited. I assure you that I will never repeat such a mistake again.

I kindly request that you keep my main account "RubayetRafsan" active, and I’m completely okay with "Samad_2g" being blocked or deactivated if necessary.

Please accept my sincere apologies, and thank you for your time and understanding.

Sincerely, RubayetRafsan

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12 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

Subject: Appeal for Submission 315444314(Problem 2094D) Dear Codeforces Team,

I received a notice that my submission(315444314) for problem 2094D was flagged for similarity with submissions from _GUARD1AN(315444314) and Necromancer_74 (315477247). I assure you I did not cheat. I believe the similarity occurred because another participant took a snapshot of my code without my permission at a public computer club. Below are details.

I solved problem 2094D independently .

I participated in the contest at a public computer club with shared workstations. During the contest, another participant approached my computer and took a snapshot of my code without my consent. I was unaware of this until receiving the violation notice. The club’s open setup likely allowed this breach, and I suspect the flagged submissions may be from individuals at the same club who used my code .

I did not share my code intentionally via platforms like ideone.com or github. I was not aware of the snapshot and did not consent to my code being used.

I deeply respect Codeforces’ rules and did not intend to violate them. I will use a private setup to prevent such incidents.

Thank you for reviewing my case.

Sincerely, _GUARD1AN

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12 months ago, hide # |
← Rev. 5  
Vote: I like it 0 Vote: I do not like it

Hey MikeMirzayanov my solutions to contest 1017 have been skipped because of an apparent violation with my submission to question G of the contest with the submission of the user AlwaysAngry for the same question. I feel this is purely coincidental because I solved the question on my own and also most of the submissions made during the contest have the same code logic, owing to the question, and hence I feel this is unfair to both of us for getting plagged out. Please do look into this matter.

Hey problem setters cry and Proof_by_QED can you help me with this? I posted this on the third party code rules blog

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12 months ago, hide # |
← Rev. 5  
Vote: I like it 0 Vote: I do not like it

..

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